No fewer than three House Democrats are running for their party’s top spot on the Appropriations Committee, a phenomenon that runs in stark contrast to Rep. Maxine Waters’ uncontested bid to lead the party on the Financial Services Committee next year.

Though Waters has been under an ethics cloud in recent years, sources said the Californian appears to have all but secured the slot being vacated by retiring Rep. Barney Frank (D-Mass.). In fact, the ethics issue has rallied the close-knit Congressional Black Caucus behind Waters, and its protective front has helped her practically lock up the Financial Services spot despite the ongoing case.

“Waters is a powerhouse,” one senior Democratic aide observed. “Approps is a totally different story.”

Rep. Norm Dicks’ (D-Wash.) surprising retirement announcement two weeks ago sparked a quick response from several of his colleagues on the Appropriations Committee who are looking to succeed him. Rep. Marcy Kaptur (Ohio), who just cleared a primary back home, is the most senior Democrat on the panel, while Rep. Nita Lowey (N.Y.) appears to be the most popular alternative. Rep. Jim Moran (Va.), another veteran appropriator, has also been making calls and could be among the dark-horse candidates.

Yet at the Financial Services Committee, everyone is deferring to Waters, the second-most-senior Democrat behind Frank and a longtime advocate for minority businesses. The 11-term lawmaker even flaunted her likely promotion in a speech last month at the Democratic convention in California, telling listeners that financial institutions are “shaking in their boots ... because Maxine Waters is going to be the next chair of the Financial Services Committee.”

Her colleagues don’t seem to be challenging that assertion. Rep. Carolyn Maloney, whose New York district encompasses much of Manhattan, recently told Roll Call, “I’m supporting Maxine.” Maloney had considered challenging Waters for the position.

Rep. Mel Watt (N.C.), one of several CBC members who also sit on Financial Services, offered similar comments shortly after Frank announced his retirement last year.

“I’m supporting her, and there are no circumstances under which I would contest that,” Watt said in December.

The CBC historically supports the seniority system for assigning committee leadership roles, noting that it helps the group’s Members ascend to top positions. Of course, Rep. Elijah Cummings (Md.) was one to buck that tradition and leapfrog Maloney after the 2010 elections to serve as the top Democrat on the Oversight and Government Reform Committee. Maloney vigorously campaigned for that position, and observers note her loss was instructive in her decision not to mount a challenge against Waters at Financial Services.

“People are acting in deference to Maxine Waters because of how active she’s been with the committee and how it would appear to be blatantly unfair if she did not end up in that chair. It’s a matter of fairness,” CBC Chairman Emanuel Cleaver (D-Mo.) said.

Still, Waters’ ascension is not without controversy. She is not an active fundraiser for her fellow House candidates, an expected duty of any lawmaker with future ambition. And the ethics case, which has dragged on for several years, concerns Financial Services issues. The panel has been investigating whether she and her staff intervened with federal regulators on behalf of a community bank in which her husband had a financial interest.

Just days before a rare public ethics trial was slated to begin in November 2010 — already more than a year after allegations first surfaced — the House Ethics Committee announced that it had uncovered new information and the proceedings would be postponed. Two staffers were placed on administrative leave following the cancellation, and internal documents leaked to the press showed that the committee’s former staff director believed the integrity of the probe had been compromised.

In July, the Ethics Committee hired Billy Martin, a partner at the law firm Dorsey &amp; Whitney, to investigate the actions of committee members and staffers in the Waters matter and determine whether and how the committee’s investigation of the California Democrat could continue. Martin’s contract was later extended and is set to expire this summer.

Though the Ethics panel announced last month that it had appointed alternates for six Members who had recused themselves from the case, the status of Martin’s report on the committee and the Waters probe remains unknown. If the committee moves to censure Waters, as it did with then-Ways and Means Chairman Charlie Rangel (D-N.Y.), her bid to move up at Financial Services could be compromised. If the findings are anything less, it’s unclear what the ramifications might be.

But Waters, Cleaver suggested, “is a victim of partisanship in Washington. Not from Members as much as the Ethics Committee.”

Amanda Becker contributed to this report.

Correction: March 14, 2012

An earlier version of the article incorrectly stated that the district of Rep. Carolyn Maloney (D-N.Y.) includes Wall Street. It does not.